1. Field of the Invention
The present invention relates to an embroidery sewing machine and more particularly to an embroidery sewing machine having an embroidery frame carrier to freely move the embroidery frame holding the embroidery fabric in two mutually perpendicular directions.
2. Description of the Related Art
Conventionally, an embroidery frame carrier of a general embroidery sewing machine is provided with an embroidery frame, a carriage to which the embroidery frame is detachably attached, a Y direction carrier mechanism to move the carriage to the direction of the width of a sewing machine bed (Y direction) and an X direction carrier mechanism to move the carriage towards direction of the length of the sewing machine bed (X direction) and the like. This embroidery frame carrier carries the embroidery frame holding work cloth to the X direction and the Y direction so that an embroidery pattern is formed on the work cloth by a sewing mechanism of the sewing machine.
In a conventional embroidery frame carrier, various structures to attach/detach the embroidery frame to the carriage have been reduced to practice. For example JP-A-2002-52284 discloses an embroidery frame carrier enabling the attachment/detachment of plurality types of embroidery frames having variously sized and shaped fabric holders to hold the work cloth.
This embroidery frame carrier is configured by an engagement mechanism to engage a connector of the embroidery frame by sliding the connector in the front-rear direction (widthwise with respect to the bed), a lock mechanism to fix the connector of the embroidery frame, which is engaged to a frame attachment position by the engagement mechanism to the carriage and a location mechanism to locate the embroidery frame to the frame attachment position.
The aforesaid engagement mechanism is configured by an engagement groove extending in the front-rear direction on an upper surface of a protrusion of the carriage and an engaging convexity elongated in the front-rear direction is formed on the lower end of the connector of the embroidery frame. The embroidery frame is attached to the attachment position by slidingly engaging the engagement convexity to the engagement groove.
The lock mechanism includes a lock member and biasing member provided on the carriage. The lock member is provided moveably from the pressure position to press the connector against the carriage and the release position to release the connector from a pressed state.
The locating mechanism is configured by a protrusion provided on the lock member and a concaving groove provided on an embroidery frame to fit with the protrusion. The embroidery frame is located in a predetermined frame attachment position by fitting the protrusion to the concave groove.
In a structure for mounting the embroidery frame to the carriage, it is important for the embroidery frame to be fixed without play in the mounted state as well as providing smooth attachment/detachment of the embroidery frame for the user. In the above described construction, the embroidery frame is fixed without vertical play by pressing the connector against the carriage by the lock mechanism.
However, since the concave groove of the location mechanism is integrally provided with the embroidery frame, there is a concern of dimensional errors of the concave grooves of the embroidery frames resulting from errors in the manufacture of embroidery frames. Therefore, in some embroidery frames, a play results from the fitting of the concave groove and the protrusion of the lock member. Because of such play, the embroidery frame is rattled in the front-rear direction (sliding direction) during the embroidery frame transfer, leading to misalignment of seams.
Since each of the concave groove and protrusion are small in shape, it is difficult for the user to see whether the protrusion is securely fitted into the concave groove. This gives rise to concerns of starting the sewing process with the connector of the embroidery frame insecurely fixed (the so called premature insertion) to the carriage which also leads to misalignment of the seams at the time of embroidery sew.
Also, in order to reliably maintain the horizontal disposition of the embroidery frame attached to the carriage, the bias on the biasing member to pressure the lock member needs to be increased. However, if the bias is increased, a burdensome operation to operate the lock mechanism will be required to resist the bias, leading to the impairment of the ease of the attachment/detachment of the embroidery frame.